/Engine/Source/Runtime/Engine/Classes/Engine/Engine.h
Renders warnings about the level that should be addressed prior to shipping
The Y position in the canvas after the last drawn string
float DrawOnscreenDebugMessages ( [UWorld](API\Runtime\Engine\Engine\UWorld) * World, [FViewport](API\Runtime\Engine\FViewport) * Viewport, [FCanvas](API\Runtime\Engine\FCanvas) * Canvas, [UCanvas](API\Runtime\Engine\Engine\UCanvas) * CanvasObject, float MessageX, float MessageY )